Humidifying apparatus

ABSTRACT

A humidifier in which an air-permeable, water-holding sheath, preferably of inverted bag-like form, is resiliently suspended in a substantially vertical air stream for vertical movement in response to variations in the weight of water held thereby, controls for supplying water to the sheath and for inducing and maintaining the air stream being actuated by such movement of the sheath. A humidistat may be provided to prevent water delivery when environmental humidity exceeds a predetermined value.

United States Patent [191 Procter [111 3,811,661 [451 May 21, 1974 1 HUMIDIFYING APPARATUS [76] Inventor: James C. Procter, R.R. No. 1,

Seymour, Ind. 47274 [22] Filed: May 22, 1972 [211 App]. No.1 255,534

[52] U.S. Cl. 261/26, 261/70, 261/105, 261/106, 261/107, 261/DIG. 15, 261/DlG. 34

[51] Int. Cl B01lf3/04 [58] Field of Search 261/26, 30, 70, 97, 99, 261/104, 105, 107, DIG. 15, DIG. 34; 126/113 [56] References Cited UNITED STATES PATENTS 7/1933 Sargent 261/99 4/1953 Snow ..261/66 2,670,941 3/1954 Feinberg 2,875,991 3/1959 Ruegsegger.... 261/66 2,939,687 6/1960 Goettl 261/26 3,157,716 11/1964 Morris 261/97 X 3,395,900 8/1968 Meek 2151/97 X 3,400,919 9/1968 Schall l l 261/D1G. 15 3,512,763 5/1970 Winton 261/DlG 15 Primary Examiner-Tim R. Miles Assistant ExaminerRichard L. Chiesa Attorney, Agent, or Firm-Hood & Coffey 57 ABSTRACT A humidifier in which an air-permeable, Water-holding sheath, preferably of inverted bag-like form, is resiliently suspended in a substantially vertical air stream for vertical movement in response to variations in the weight of water held thereby, controls for supplying water to the sheath and for inducing and maintaining the air stream being actuated by such movement of the sheath. A humidistat may be provided to prevent water delivery when environmental humidity exceeds a predetermined value.

15 Claims, 3 Drawing Figures PATENTEDMAYZI 1974 sum '2 BF 2 Fig.2

HUMIDIFYING APPARATUS The present invention relates to a humidifier and the primary object of the invention is to provide an extremely simple, inexpensive, trouble-free automatic humidifier with a minimum of moving parts, in which the water supply to a reservoir and the operation of a means for inducing an air flow through the equipment will be controlled through the movement of a watercarrying, air-permeable sheet in accordance with variations in the weight of water currently carried by such a sheet disposed in the path of an air stream. A further object of the invention is to'provide a humidifier in which the air stream moves upwardly to pass thorugh the water-laden sheet and thence to be discharged into the space to be humidified at a point near the top of that space.

Still another object of the invention is to provide means, movable with a resiliently-suspended watercarrying sheet, for shutting off the supply of water to a reservoir whenever the water burden of the sheet exceeds a predetermined value, regardless of the water level in the reservoir, so that the water-carrying sheet may never become overladen. Another object is to provide means responsive to the degree of humidity currently existing in the space to be controlled and capable of prohibiting water supply to the reservoir whenever such environmental humidity exceeds a predetermined value.

' Still further objects of the invention will appear as the description proceeds.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and'described, so long as the scope of the appended claims is not violated. 1

1n the drawings:

FIG. 1 is a fragmental perspective view, somewhat diagrammatic, of the upper regions of a humidifier constructed in accordance with the present invention, parts being broken away for clarity of illustration;

FIG. 2 is a somewhat diagrammatic perspective of the entire humidifier, drawn to a smaller scale and with parts of the. housing broken away; and V FIG. 3 is a diagram illustrating parts of the humidifier and their operational association with one satisfactory form of circuitry. I

Referring more particularly to the drawings, it will be seenthat l have illustrated a vertically elongated housing indicated generally by the reference numeral 10. Desirably, the housing will be approximately 7-% feet tall, 14 inches wide and 3% inches deep so that it may, if desired, be fitted between studs and between finished surfaces of a conventional house wall. The housing is provided with an inlet port 11 near its bottom and with an outlet port 12 near its top, said ports being preferably guarded by metal or plastic mesh panels, louvers or the like. The housing may, of course, be located within a room rather than inside a room wall as suggested above, in which case it will braced suitably attached to the wall or otherwise bracked against toppling. In case it is to be so used, it may be externally decorated in any desired manner, as by printing its external surfaces with mally closed valve 15 is installed in the line to control flow therethrough. Preferably, a solenoid valve will be used, the solenoid 16 being arranged to open the valve upon energization thereof.

A float 17 is disposed preferably in a separate compartment open at its bottom to the main body of the reservoir. The float may be of the inverted cup type to rise and fall with the water level in the reservoir 13. A metal strap 17 is fixed to a rock shaft 18 suitably journalled on a transverse axis adjacent the reservoir with the distal end of said strap disposed in the rising path of the float. At one end, the rock shaft 18 is bent to define an arm 19 terminating in an upwardly-opening hook; and at its other end the rock shaft carries a bracket 20 supporting a mercury switch 21 connected in the energizing circuit for the solenoid 16. The switch 21 is soarranged, of course, that it is closed when its rear end is down and is open when the float is in its illustrated position.

The reservoir 13 is open at its top and is formed to provide laterally elongated front and rear walls 22 and 23 having exposed upper edges. Suitable brackets 24 depend below the reservoir 13 adjacent its opposite ends, being secured either to the reservoir or to the rear wall of the housing 10,and coiled tension springs 25,

25 are suspended from such brackets. A transverse rod 26 is, in turn, resiliently supported at its opposite ends by said springs for vertical movement within the housing 10.

The rod 26 is a part of, or is fixedly secured to, an airpermeable frame 27 of any suitable form and a sheath indicated generally by the reference numeral 28 is suitably draped over said frame to move therewith. In a preferred form, the sheath 28 may take the form of an open-mouthed, inverted bag with front and rear sheets 29 and 30 of substantial expanse joined together (but not necessarily in an air tight manner) below and preferably above the rod 26 and with front and rear upward extension 34 and 35.

The sheath 28 is preferably a transversely-ribbed polyester knit, reticulate fabric which is capable of holding substantial quantities of water in its interstices but is substantially devoid of capillary properties. Over each of the reservoir walls 22 and 23there is draped a strip of wicking material 31 dipping below the normal water level in the reservoir and depending substantially to the bottom edge of the associated reservoir wall on the outside of the reservoir. 1 have found terry cloth to beone satisfactory form of wicking material, but of course other materials having relatively high capillary characteristics may be used including almost any cotton cloth or even a multiplicity of separate strings.

. of the mesh 32, so that the extensions are in contact with the outer surface of the mesh and extend inwardly below, but out of contact with, the fingers 33.

With this arrangement, the wicking material 31 is maintained in a saturated condition as long as the water level in the reservoir 13 is sufficiently high. Water fills the interstices of the mesh material and drips from the fingers 33 onto the internal, ribbed surfaces of the sheath 28. The grooves between the internal ribs further distribute the water laterally of the sheath and the water flows downwardly along the sheath, penetrating the sheath to pass the rod 26, until, under some circumstances, the openings in the sheath material are all filled with water.

Of course, as water accumulates on the sheath, the gross weight of the frame 27, sheath 28 and its burden gradually increases whereby the springs 25 will be elongated and the frame 27 with the sheath will move downwardly.

Guided for reciprocation in a preforated stationary ear 36 and a similar ear 37 carried by the rod 26 is a rod 38 formed at its upper end to provide a toe 39 which rests in the hook of the arm 19 of the rock shaft 18, slightly overbalancing the strap 17' to impart a clockwise bias to the shaft as viewed from the left in FlG. 1. Thus, so long as theweight of the rod 38 is impressed upon the arm 19, the switch 21 will be open and the valve 15 will be closed.

A collar 40 is adjustably fixed to the rod 38 and is disposed in the rising path of the ear 37. When the water burden carried by the sheath 28 is diminished to a predetermined quantity, the sheath 28 and frame 27 will be lifted by the springs 25 so that the ear 37 engages the collar 40 and lifts the rod 38 relative to the rock shaft arm 19, permitting the weight of the strap 17 to turn the rock shaft 18 in a counterclockwise direction to close the switch 21, thus energizing the solenoid 16 to open the valve 15 to permit water to flow into the reservoir 13. As the water level rises in the reservoir, the float 17 will rise to engage the distal end of the strap 17 and drive it in a direction to open the switch 21. Even if, for any reason, the float should fail to rise, as water is supplied to the sheath through the wicking element 31, the gross weight of the sheath, frame and burden will increase to move the rod 26 downwardly away from the collar 40, thus allowing the weight of the rod 38 again to be impressed upon the arm 19 to open the switch 21.

Means is provided to establish and maintain a flow of air into the housing through the inlet port 11, upwardly through the sheath 28 and outwardly through the port 12. Of course, as the air stream permeates and penetrates the reticulate sheath, it will absorb and entrain moisture. If the rate of absorption and entrainment is precisely equal to the rate of delivery of water to the sheath through the wicking means, the system will continue to operate in a balanced condition. The rate of absorption of moisture from the sheath into the air stream will be largely a function of the relative humidity of the air entering the inlet port 11 and of the velocity of the air stream so that such a balanced condition will occur only occasionally. Ordinarily, the air stream inducing means will operate only periodically.

In the illustrated embodiment of the invention, a rotary blower 41 is shown as the air flow-inducing means. Such a blower may conveniently be installed near the bottom of the housing 10 and centered relative to the inlet opening 11. If desired, the blower may be hooded to direct its exhaust to the small end of a funnel 42 whose upper, enlarged end may freely receive the lower end of the sheath 28. An electric motor 43 is connected to drive the blower 41.

Guided in a plurality of ears 48 outstanding from the frame 27 is a reciprocable rod 45 preferably having a head 46 at its upper end. A stem 47 fixedly extends outwardly from the rod 45. A normally open switch mechanism 48 is supported in the housing 10 in the region of the rod 45 and includes an inwardly extending rock shaft or actuator 49 having an arm 50 terminating in an upwardly opening hook in which is normally supported the distal end of the stem 47. The weight of the rod 45 and stem 47 is sufficient to hold the switch mechanism 48 in switch-closed position. When the sheath 28 rises as its water burden is decreased, the uppermost ear 44 will engage the rod head 46 to lift the stem 47 away from the hooked arm 50 to permit the switch to open.

As is most clearly to be seen in FIG. 3, the switch mechanism 48 dominates the energizing circuit for the blower motor 43. A power panel 51 includes terminals 52 and 53 connected to one side 54 of a power line, and a terminal 55 connected to the other side 56 of such line. A wire 57 leads from terminal 52 to one side of the switch mechanism 48, while a wire 58 leads from the other side of said switch mechanism to one terminal of the motor 43 and a wire 59 leads from the other tenninal of said motor to the panel terminal 55. Thus, the blower 41 will be driven whenever the switch mechanism 48 is in closed condition.

A wire 60 leads from the panel terminal 53 to one side of a humidistat 61. A wire 62 leads from the other side of the humidistat to one side of the switch 21 and a wire 63 connects the other side of the switch 21 to one side of the solenoid 16, a wire 64 leading from the other side of said solenoid to the panel terminal 55. It will be understood, of course, that the humidistat 61 includes a switch which will be closed only when the environmental humidity is below a predetermined value.

When the system is initially installed, of course the reservoir 13 will be empty and the float 17 will be in its down position. The sheath 28 will be dry so that the frame 27 will be in its uppermost position with the ear 37 engaging the collar 40 to hold the weight of the rod 38 off the arm 19 of the rock shaft 18. Thus, the switch 21 will stand in its closed position. If the humidistat is calling for humidity, the solenoid 16 will therefore be energized to open the valve 15 to supply water to the reservoir 13.

With the frame 27 in its uppermost position, the rod 45 and stem 47 will be supported out of contact with the arm 50 whereby the switch mechanism 48 will be open and the blower 41 will not be operating.

As water continues to flow to the reservoir 13, the liquid level therein will rise into contact with the inner edges of the wicking strips 31 and water will begin to drip from the fingers 33 onto the inner surfaces of the opposed sheets 29 and 30 of the sheath 28.

As the water level in the reservoir continues to rise, the float 17 will also rise. If the float 17 reaches a predetermined height before the sheath 28 acquires a sufficient water burden to permit the weight of the rod 38 to be applied to the arm 19, the float will engage the distal end of the strap 17 to rock the shaft 18 in a clockwise direction to open the switch 21, deenergize the solenoid 16 and permit the valve 15 to close. If, on the contrary, the sheath 28 should acquire a sufficient water burden before the float 17 rises far enough to open the switch 21, the weight of the rod 38 will be impressed upon the arm 19 to rock the shaft 18 to open the switch 21. In either case, the supply of water to the reservoir 13 will be cut off before the reservoir overflows.

Meantime, as the sheath 28 and frame 27 descend against the resilient resistance of the springs 25, the weight of the rod 45 and stem 47 will be applied to the arm 50 to close the switch 48, thus energizing the blower motor 43. The blower will draw in air through the port 11, in a region wherein the air is relatively cool, and will force the air stream to flow upwardly through the funnel 42 and sheath 28, to pick up water from the interstices of the sheath and deliver it to the space to be humidified in the upper regions of that space where the air will be relatively warm. Thus, contrary to conventional humidifiers, the moisture-laden air will not emerge from the housing into a relatively cool region whereby the moisture might be condensed undesirably, but instead will emerge into a relatively warm region wherein the ambient air is able to accept and disperse moisture from the emerging stream.

For as long as the sheath 28 remains below a predetermined position, the stem 47 will hold the switch mechanism 48 in closed condition and the blower 41 will continue to operate. The system is so proportioned and designed that the moving air stream will always entrain moisture from the sheath at a rate in excess of the rate at which moisture is delivered to the sheath through the wicking material 31 and the mesh 32. Thus, the frame 27 and sheath 28 will gradually rise as its burden decreases until, when the stem 47 leaves the arm 50, the energizing circuit for the motor 43 will be broken. Depending upon where the water level stands in the reservoir 13 at that time, the supply of water to the sheath from the reservoir may continue so that the frame 27 will again move downwardly to close the switching mechanism 48. Eventually, of course, the water level in the reservoir will fall below the inner edge of the wicking mechanism 31 so that, when the burden carried by the sheath 28 falls to a value which will stop the blower, the frame 27 will continue to rise until the weight of the rod 38 is removed from the arm 19 and the switch 21 will be closed to replenish the supply of water in the reservoir 13 whereupon the above described cycle will be reinitiated.

it will be appreciated that numerous variations and modifications in the specific structure illustrated may be made without departing from my invention, so long as the basic principle of control of the operation of the device through vertical movement of the sheath and/or frame in response to variations in the water burden thereof, is utilized. For instance, the blower 41 might be replaced by other air-flow-inducing means such as, for instance, an electrically energized heater near the bottom of the housing 10 to establish a thermo-siphon movement of air.

While the disclosed materials for the strips 31, 32 and the sheath 28 are believed to be optimum, other materials having similar characteristics could be used to replace them and, in fact, the strip 32 might be omitted without departing from the scope of my invention.

In some instances, it might be desirable to establish a thermo-siphon-induced air stream by means of a duct leading from a central heating system to the lower portion of the housing 10, with or without valve means dominated by the switch mechanism 48. [presently believe, however, that there are advantages in the use of the blower 41 whereby the moisture-laden air stream will be delivered to the space to be humidified at a temperature lower than that of the atmospheric temperature in the region of delivery.

I claim:

1. A humidifier comprising a vertically-elongated housing, air inlet and outlet ports near the opposite ends of said housing, respectively, a water reservoir within said housing near the top thereof, means including a valve for controlling flow of water to said reservoir, a sheath of water-holding air-permeable material suspended within said housing below said reservoir and adapted to receive from said reservoir water dispersed over the surface of said sheath, means yieldably suspending said sheath for vertical movement in said housing in response to variations in the weight of water so carried by said sheath, means responsive to such movement of said sheath for dominating said valve, means for inducing flow of air through said sheath between said inlet and outlet ports and means responsive to such movement of said sheath for dominating said flowinducing means.

2. The humidifier of claim 1 including a humidistat responsive to ambient humidity and effective to render said valve-dominating means ineffective to open said valve when such ambient humidity exceeds a predetermined value.

3. The humidifier of claim 1 in which said sheath material is substantially without capillary capacity, and means for transferring water from said reservoir to said sheath surface, comprising a sheet of wicking material dipping into said reservoir and draped over an edge thereof to depend outside said reservoir between said sheath and the reservoir wall.

4. The humidifier of claim 3 including a strip of finemesh, nonabsorbent material interposed between said wicking material and said sheath.

5. The humidifier of claim 4 in which said sheath material is formed to define a multiplicity of verticallyspaced, substantially horizontally-extending ribs and said mesh material is formed to define a plurality of laterally-spaced, downwardly-depending fingers extending below the lowermost edge of said wicking material.

6. The humidifier of claim 1 in which said flowinducing means is an electrically-driven blower, an energizing circuit for said blower and said means responsive to such movement of said sheath is a switch in said circuit including an element movable with said sheath.

7. A humidifier comprising a vertically-elongated housing, air inlet and outlet ports near the opposite ends of said housing, respectively, a water reservoir within said housing near the top thereof, a sheath of water-holding, air-permeable material suspended within said housing below said reservoir and adapted to receive from said reservoir water dispersed over the surface of said sheath, means yieldably suspending said sheath for vertical movement in said housing in response to variations in the weight of water so carried by said sheath, means for inducing flow of air through said sheath between said inlet and outlet ports and means responsive to such movement of said sheath for dominating said flow-inducing means.

8. The humidifier of claim 3 in which said sheath material is substantially without capillary capacity, and means for transferring water from said reservoir to said sheath surface, comprising a sheet of wicking material dipping into said reservoir and draped over an edge thereof to depend outside said reservoir between said sheath and the reservoir wall.

9. The humidifier of claim 8 including a strip of finemesh, nonabsorbent material interposed between said wicking material and said sheath.

10. The humidifier of claim 9 in which said sheath material is formed to define a multiplicity of verticallyspaced, substantially horizontally-extending ribs and said mesh material is formed to define a plurality of laterally-spaced, downwardly-depending fingers extending below the lowermost edge of said wicking material.

11. A humidifier comprising a vertically-elongated housing having an exit port near its top and an inlet port near its bottom, a reservoir within said housing near its top, an air-permeable frame within said housing below said reservoir, means resiliently yieldably suspending said frame for vertical movement in said housing, wicking means arranged to dip into said reservoir and to overlie the external walls of said reservoir, dispersing means overlying said wicking means, a sheath of reticulate material draped over said frame and having upward extensions overlying said dispersing means in intimate contact therewith, means for supplying water to said reservoir including valve means for controlling fiow through said supplying means, means movable in response to liquid-level variations in said reservoir, means operatively associated with said last-named means to ensure closure of said valve when the liquid in said reservoir is above a predetermined level, means yieldably resisting valve-opening movement of said last-named means, means moving with said frame to cancel the resistance of said resisting means upon upward movement of said frame, a humidistat responsive to environmental humidity near said inlet port and effective to prevent opening of said valve when such environmental humidity exceeds a predetermined value, means for inducing air flow from said inlet port through said sheath to said outlet port, and means moving with said frame and dominating said air-flow-inducing means.

12. In a humidifier, a reticulate sheet substantially without capillary capacity, a housing within which said sheet is substantially vertically suspended, said housing having an outlet port, a water reservoir near the top of said housing, said reservoir having an upstanding wall, wicking material draped over an upwardly-facing edge of said wall with one end inside said reservoir and below the normal reservoir water level and its other end disposed outside the reservoir near the bottom of said wall, and a layer of non-absorptive, fine-mesh material overlying the wicking material in the region outside said wall, the upper portion of said sheet overlying and bearing upon said fine-mesh material, and means for causing an air stream to flow through said sheet to and through said outlet port.

13. The combination of claim 12 in which said finemesh material is formed to provide a series of laterallyseparated fingers depending below the lowermost end of said wicking material.

14. The combination of claim 13 in which said sheet is formed to provide a vertically-spaced series of substantially horizontal ribs on its surface facing said reservoir.

15. In a humidifier, an air-permeable, water-holding sheet, means resiliently supporting said sheet for vertical movement in response to variations in the weight of water held thereby, means for delivering water to said sheet, means for inducing a flow of air through said sheet, and means moving with said sheet to control said water delivering means and said air flow inducing means.

M14050 UNITED STATES PATENT OFFICE 5'69) CERTIFICATE OF CQRRECTIDN Patent No. 1, Da May 21, 1974 lm rentorfs James C. Procter It is certified that error appears in the-abova-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 1, line 64, "braced" should be be line 65 "bracked" shouldbe braced Y Column 2, line 44, "extension" should be extensions line 65 should read The upper edges of the sheath extensions 34 and 35".

Column 3, line 19, "preforated" should be perforated Column 4, line 6, "48" should be 44 Column 7, line 4 (Claim 8, line 1) should read Th humidifier of claim 7 in which said sheath ma- Signed and sealed this 15th day of October 1974,,

(SEAL) Attest:

McCOY M. GIBSON JR. 0. MARSHALL DANN iAttesting Officer Commissioner of Patents 

1. A humidifier comprising a vertically-elongated housing, air inlet and outlet ports near the opposite ends of said housing, respectively, a water reservoir within said housing near the top thereof, means including a valve for controlling flow of water to said reservoir, a sheath of water-holding air-permeable material suspended within said housing below said reservoir and adapted to receive from said reservoir water dispersed over the surface of said sheath, means yieldably suspending said sheath for vertical movement in said housing in response to variations in the weight of water so carried by said sheath, means responsive to such movement of said sheath for dominating said valve, means for inducing flow of air through said sheath between said inlet and outlet ports and means responsive to such movement of said sheath for dominating said flow-inducing means.
 2. The humidifier of claim 1 including a humidistat responsive to ambient humidity and effective to render said valve-dominating means ineffective to open said valve when such ambient humidity exceeds a predEtermined value.
 3. The humidifier of claim 1 in which said sheath material is substantially without capillary capacity, and means for transferring water from said reservoir to said sheath surface, comprising a sheet of wicking material dipping into said reservoir and draped over an edge thereof to depend outside said reservoir between said sheath and the reservoir wall.
 4. The humidifier of claim 3 including a strip of fine-mesh, nonabsorbent material interposed between said wicking material and said sheath.
 5. The humidifier of claim 4 in which said sheath material is formed to define a multiplicity of vertically-spaced, substantially horizontally-extending ribs and said mesh material is formed to define a plurality of laterally-spaced, downwardly-depending fingers extending below the lowermost edge of said wicking material.
 6. The humidifier of claim 1 in which said flow-inducing means is an electrically-driven blower, an energizing circuit for said blower and said means responsive to such movement of said sheath is a switch in said circuit including an element movable with said sheath.
 7. A humidifier comprising a vertically-elongated housing, air inlet and outlet ports near the opposite ends of said housing, respectively, a water reservoir within said housing near the top thereof, a sheath of water-holding, air-permeable material suspended within said housing below said reservoir and adapted to receive from said reservoir water dispersed over the surface of said sheath, means yieldably suspending said sheath for vertical movement in said housing in response to variations in the weight of water so carried by said sheath, means for inducing flow of air through said sheath between said inlet and outlet ports and means responsive to such movement of said sheath for dominating said flow-inducing means.
 8. The humidifier of claim 3 in which said sheath material is substantially without capillary capacity, and means for transferring water from said reservoir to said sheath surface, comprising a sheet of wicking material dipping into said reservoir and draped over an edge thereof to depend outside said reservoir between said sheath and the reservoir wall.
 9. The humidifier of claim 8 including a strip of fine-mesh, nonabsorbent material interposed between said wicking material and said sheath.
 10. The humidifier of claim 9 in which said sheath material is formed to define a multiplicity of vertically-spaced, substantially horizontally-extending ribs and said mesh material is formed to define a plurality of laterally-spaced, downwardly-depending fingers extending below the lowermost edge of said wicking material.
 11. A humidifier comprising a vertically-elongated housing having an exit port near its top and an inlet port near its bottom, a reservoir within said housing near its top, an air-permeable frame within said housing below said reservoir, means resiliently yieldably suspending said frame for vertical movement in said housing, wicking means arranged to dip into said reservoir and to overlie the external walls of said reservoir, dispersing means overlying said wicking means, a sheath of reticulate material draped over said frame and having upward extensions overlying said dispersing means in intimate contact therewith, means for supplying water to said reservoir including valve means for controlling flow through said supplying means, means movable in response to liquid-level variations in said reservoir, means operatively associated with said last-named means to ensure closure of said valve when the liquid in said reservoir is above a predetermined level, means yieldably resisting valve-opening movement of said last-named means, means moving with said frame to cancel the resistance of said resisting means upon upward movement of said frame, a humidistat responsive to environmental humidity near said inlet port and effective to prevent opening of said valve when such environmental humidity exceeds a predetermined value, means for inducing air flow from sAid inlet port through said sheath to said outlet port, and means moving with said frame and dominating said air-flow-inducing means.
 12. In a humidifier, a reticulate sheet substantially without capillary capacity, a housing within which said sheet is substantially vertically suspended, said housing having an outlet port, a water reservoir near the top of said housing, said reservoir having an upstanding wall, wicking material draped over an upwardly-facing edge of said wall with one end inside said reservoir and below the normal reservoir water level and its other end disposed outside the reservoir near the bottom of said wall, and a layer of non-absorptive, fine-mesh material overlying the wicking material in the region outside said wall, the upper portion of said sheet overlying and bearing upon said fine-mesh material, and means for causing an air stream to flow through said sheet to and through said outlet port.
 13. The combination of claim 12 in which said fine-mesh material is formed to provide a series of laterally-separated fingers depending below the lowermost end of said wicking material.
 14. The combination of claim 13 in which said sheet is formed to provide a vertically-spaced series of substantially horizontal ribs on its surface facing said reservoir.
 15. In a humidifier, an air-permeable, water-holding sheet, means resiliently supporting said sheet for vertical movement in response to variations in the weight of water held thereby, means for delivering water to said sheet, means for inducing a flow of air through said sheet, and means moving with said sheet to control said water delivering means and said air flow inducing means. 